| 摘要 |
The present invention relates to a polyethylene composition comprising a base resin which comprises (A) a first ethylene homo- or copolymer fraction, and (B) a second ethylene homo- or copolymer fraction, fraction (A) having a lower molecular weight than fraction (B), wherein the polyethylene composition has a MFR 5 of not more than 0.2 g/10 min, determined according to ISO 1133 at 190 °C and at a load of 5.0 kg; a MFR 21 of not more than 5.0 g/10 min, determined according to ISO 1133 at 190 °C and at a load of 21.6 kg, and the relationship between pressure resistance (STPR) according to ISO 1167-1:2006, measured at 12.4 MPa and 20 °C in hours and tensile modulus (TM), measured according to ISO 527-2:1993 in MPa fulfils the following inequation: log (STPR) [h] > (-4.5936 + 0.00624 * TM [MPa]) + 0.35. The invention further relates to a process for the production of such a polyethylene composition and the use of such a polyethylene composition for the production of a pipe or a fitting and for increasing the lifetime of a pipe or a fitting. |
